text: β-W was first observed by Hartmann et al. in 1931 as part of the dendritic metallic deposit formed on the cathode after electrolysis of phosphate melts below 650°C. In the beginning stages of research into β-W, oxygen was commonly found to promote the formation of the β-W structure, thus discussions of whether the β-W structure is a phase of single-element tungsten or a tungsten suboxide were long-standing, but ever since the 1950s there has been a lot of experimental proof showing that the oxygen in β-W thin films is in a zero valence state, and thus the structure is a true allotrope of tungsten. 
  While the initial interest in β-W thin films was driven by its superconducting properties at low temperatures, the discovery of giant spin Hall effect in β-W thin films by Burhman et al. in 2012 has generated new interest in the material for potential applications in spintronic magnetic random access memories and spin-logic devices.